TWI748273B - Electro-optic device and method of operating the same - Google Patents

Abstract

An electro-optical device includes an electrophoretic medium containing a dispersion of a plurality of particles in a fluid, and the particles are configured to migrate in the fluid in a direction corresponding to an applied electric field. The plurality of particles include: a first type particle having a first charge with a first charge polarity, a second type particle with a second charge having a second charge polarity, and a third charge having the second charge polarity. Three kinds of particles. The polarity of the first charge is opposite to the polarity of the second charge, and the third particles are configured to migrate in the fluid in a direction corresponding to the applied magnetic field gradient.

Description

Electro-optical device and method of operating the electro-optical device

This application claims the priority of U.S. Provisional Application No. 62/752,614 filed on October 30, 2018, and the entire content of the application is incorporated herein by reference.

The technology described herein relates to an electro-optical device, which includes an electrophoretic medium containing charged particles and magnetically responsive particles, which can use a specialized instrument (stylus) or printing Head) and related methods to operate (addressed).

By way of reference, the entire contents of all the following U.S. patents and published applications are incorporated herein.

The term "electro-optics" as applied to materials or displays is used herein in its normal meaning in the imaging field, and refers to materials with first and second display states, the first and second display states being at least one The optical properties are different, and the material is transformed from its first display state to its second display state by applying an electric field to the material. Although the optical property is usually the color that the human eye can perceive, it can also be other optical properties, such as optical transmission, reflection, luminescence, or in the case of a display intended for machine reading, it is outside the range of visible light Pseudo-color in the sense of reflection changes of electromagnetic wavelengths.

The term "gray state" is used in this article in its normal meaning in the imaging field, referring to the state between the two extreme optical states of the pixel, and does not necessarily mean the black-white transition between these two extreme states . For example, the following E Ink patents and published applications record electrophoretic displays with extreme states of white and dark blue, so that the "gray state" in the middle is actually light blue. Of course, as described above, the change in optical state may not be a color change at all. Hereinafter, the terms "black" and "white" may be used to refer to the two extreme optical states of the display, and should be understood to generally include extreme optical states that are not strictly black and white, such as the aforementioned white and dark blue states. Hereinafter, the term "monochrome" may be used to refer to a driving scheme that only drives the pixel to its two extreme optical states without an intervening gray state.

Some electro-optical materials are solid in the sense that they have a solid outer surface, although they may (and often do) have internal spaces filled with liquid or gas. Hereinafter, for convenience, such a display using solid electro-optical materials may be referred to as a "solid electro-optical display." Therefore, the term "solid-state electro-optical display" includes rotating two-color member displays, packaged electrophoretic displays, microcell electrophoretic displays, and packaged liquid crystal displays.

The terms "bistability" and "bistability" are used herein in their conventional meanings in the field, and refer to displays including display elements having first and second display states, the first and The second display state is different in at least one optical property, and after any given element is driven by an addressing pulse of a finite period to obtain its first or second display state, after the addressing pulse ends , That state will remain for a period of at least several times (for example, at least four times) the minimum period of the address pulse required to change the state of the display element. U.S. Patent No. 7,170,670 pointed out that some electrophoretic displays with gray-scale function particles are not only stable in their extreme black and white states, but also stable in the middle gray state, and some Other types of electro-optical displays have the same situation. Although for convenience, this article may use the term "bistable" to cover both bistable and multi-stable displays, but such displays are appropriately called "multi-stable" rather than bistable.

An electro-optical display that has been the subject of a large number of research and development for many years is a particle-based electrophoretic display, in which a plurality of charged particles move through a fluid under the influence of an electric field. When compared with a liquid crystal display, an electrophoretic display can have the following attributes: good brightness and contrast, wide viewing angle, state bistability, and low power consumption. However, the long-term image quality of these displays hinders their popular use. For example, particles constituting electrophoretic displays tend to settle, resulting in insufficient service life of these displays.

As mentioned above, the electrophoretic medium requires fluid to be present. In most of the prior art of electrophoretic media, the fluid is liquid, but the electrophoretic media can be manufactured using gas phase fluid; see, for example, Kitamura, T., et al., "Electrical toner movement for electronic paper displays (Electrical toner Movement for electronic paper-like display", IDW Japan, 2001, Paper HCS1-1, and Yamaguchi, Y. et al., "Toner display using insulative particles charged triboelectrically)", IDW Japan, 2001, Paper AMD4-4). See also U.S. Patent Nos. 7,321,459 and 7,236,291. Such a gas system electrophoresis medium, when the medium is used in an orientation that allows particles to settle, for example, in a signboard where the medium is arranged on a vertical plane, it seems that it is easily affected by the same as the liquid system electrophoresis medium. Caused by the problem of particle sedimentation. Indeed, the problem of particle sedimentation seems to be more serious in the electrophoretic medium of the gas system than in the electrophoresis medium of the liquid system, because the lower viscosity of the gas suspension fluid will make the electrophoretic particles faster than the liquid fluid. The land subsided.

Mass transfer to the Massachusetts Institute of Technology (MIT), E Ink, E Ink California, Inc. and related companies, or patents and applications under its name that record electrophoretic media and microcell electrophoresis media for packaging and other electro-optics Various technologies of the medium. The encapsulated electrophoretic medium includes a large number of small capsules, and each small capsule itself includes an internal phase and a capsule wall surrounding the internal phase. The internal phase contains electrophoretic movable particles in the fluid medium. Generally, the vesicles themselves are held in a polymeric binder to form a coherent layer between the two electrodes. In a microcell electrophoretic display, the charged particles and the fluid are not encapsulated in microcapsules, but instead remain in a plurality of cavities formed in a carrier medium (usually a polymer film). The technologies documented in these patents and applications include: (a) Electrophoretic particles, fluids, and fluid additives; see, for example, U.S. Patent Nos. 7,002,728, 7,679,814, 9,759,980, and 6,870,661; (b) Capsule, adhesive and encapsulation process; see, for example, U.S. Patent Nos. 6,922,276 and 7,411,719; (c) The structure of micelles, wall materials, and methods of forming micelles; see, for example, U.S. Patent Nos. 7,072,095 and 9,279,906; (d) Methods for filling and sealing micelles; see, for example, U.S. Patent Nos. 7,144,942 and 7,715,088; (e) Films and sub-components containing electro-optical materials; see, for example, U.S. Patent Nos. 6,982,178 and 7,839,564; (f) Backplanes, adhesive layers and other auxiliary layers and methods used in displays; see, for example, U.S. Patent Nos. 7,116,318 and 7,535,624; (g) Color formation and color adjustment; see, for example, U.S. Patent Nos. 7,075,502 and 7,839,564; (h) A method for driving a display; see, for example, U.S. Patent Nos. 7,012,600 and 7,453,445; (i) Application of the display; see, for example, U.S. Patent Nos. 7,312,784 and 8,009,348, and U.S. Patent Application Publication No. US2017/0336896; and (j) Non-electrophoretic displays, as described in U.S. Patent No. 6,241,921 and U.S. Patent Application Publication No. 2015/0277160; and applications of packaging and microcell technology other than displays; see, for example, U.S. Patent Application Publication No. 2015/0005720 and 2016/0012710.

Many of the aforementioned patents and applications recognize that the walls surrounding the discrete microcapsules in the encapsulated electrophoretic medium can be replaced by a continuous phase, thereby producing a so-called polymer dispersion type electrophoretic display, wherein the electrophoretic medium includes a plurality of Discrete electrophoretic fluid droplets and continuous-phase polymer materials, and even if there is no discrete capsule combined with each individual droplet, the discrete electrophoretic fluid fluid in such a polymer dispersion electrophoretic display can be combined. Drops are considered capsules or microcapsules; see, for example, the aforementioned U.S. Patent No. 6,866,760. Therefore, based on the purpose of this application, such polymer dispersion electrophoretic media is regarded as a subclass of encapsulated electrophoretic media.

There are a variety of systems that can be used to use a stylus to make electro-optical displays work. For example, a stylus can be used to take notes on some tablets. When the user moves the stylus over the surface of the electro-optical display, the electro-optical display activates the corresponding pixels on which the stylus passes over it based on the position of the stylus detected by the electro-optical display. The corresponding pixels. Some magneto-responsive displays can operate with a stylus that contains magnets and/or generates a magnetic field.

Existing writable electro-optical display systems are limited in the number of colors that can be provided using electrophoretic media. Therefore, there is a need for an improved electrophoresis-based writable device that can allow users to generate images with multiple colors.

In a first aspect of the present invention, an electro-optical device includes: a first surface on the viewing side; a second surface on the opposite side of the first surface; an electrophoretic medium disposed on the light-transmitting conductive layer and the pixel Between the arrays of electrodes and the fluid includes a plurality of particles, the plurality of particles include: (1) a first type of particle with a first color and a first charge polarity; (2) a second type of particle Color, a second-charged second particle of a second charge polarity; and (3) a third color, a third-charged particle of the second charge polarity, wherein the first, second, and third particles The colors are different from each other, the polarity of the first charge is opposite to the polarity of the second charge, the plurality of particles are configured to migrate in the fluid in the direction corresponding to the applied electric field, and the third type of particles The system is configured to migrate in the fluid in a direction corresponding to the applied magnetic field gradient, and the second kind of particles have an electric field threshold, so that (a) a voltage is applied between the light-transmitting conductive layer and the pixel electrode The voltage potential difference generates an electric field stronger than the critical value of the electric field and has the polarity to drive the second particles to abut the light-transmitting conductive layer, so that the pixel corresponding to the pixel electrode is on the first surface. Display the second color; (b) applying a voltage potential difference between the light-transmitting conductive layer and the pixel electrode to generate an electric field that is stronger than the critical value of the electric field to drive the first particles to abut the light-transmitting conductive layer Polarity, so that the pixel corresponding to the pixel electrode displays the first color on the first surface; (c) Once the first color is displayed on the first surface, between the light-transmissive conductive layer and the pixel electrode The voltage potential difference is applied to generate an electric field weaker than the critical value of the electric field, which has the polarity to drive the third particles to abut the light-transmitting conductive layer, so that the pixel corresponding to the pixel electrode displays the third color.

In another aspect of the present invention, a method of operating an electro-optical device, wherein the electro-optical device includes: (a) a first surface on the viewing side; (b) a second surface on the opposite side of the first surface Surface; (c) an electrophoretic medium, which is arranged between the light-transmitting conductive layer and the array of pixel electrodes, and includes a plurality of particles in the fluid, the plurality of particles include: (1) having a first color and a first charge polarity The first particle of the first charge; (2) The second particle of the second charge with the second color and the second charge polarity; and (3) The third charge with the third color and the second charge polarity The third kind of particles, wherein the first, second and third colors are different from each other, wherein the first charge polarity is opposite to the second charge polarity, and the plurality of particles are formed in the flow The body moves in the direction corresponding to the applied electric field, and the third particles are configured to move in the fluid in the direction corresponding to the applied magnetic field gradient, including the following steps: (A) to include The stylus with the magnetic tip contacts the first position on the first surface of the device to make the third particles migrate towards the first position; and (B) the stylus with the magnetic tip contacts the device again with the stylus The first position on the first surface allows the second type of particles to migrate toward the first position.

Hereinafter, the above-mentioned aspects and embodiments, as well as additional aspects and embodiments are further explained. Other aspects of the present invention will be easily understood by the following description. The application is not limited to this form, so these aspects and/or embodiments can be used alone, together, or in any combination of two or more.

Various embodiments of the present invention relate to electro-optical displays of electrophoretic media and particle systems that can operate electrically and magnetically. Various embodiments of the present invention can be configured to provide both global and partial operational capabilities. This full operational capability can be used to create a solid color state, such as white or black, which is considered an "erase" state. The overall operating state can be electrically controllable. For example, the display may include electrodes on opposite sides of the electro-optical layer of the particle system of the display, and the electrodes may be operated to create a suitable electric field to set the ink to a uniform color state. The display may include a controller for controlling the electric field applied to the electrophoretic particles. The controller can apply a static electric field or a time-dependent electric field, which is a waveform. This local operating capability can be provided by more than one writing implements that generate electric or magnetic fields. The term "writing instrument" used in this article includes a stylus.

As used in this article, particles are referred to as "magnetic", "magnetically reactive", "responsive to magnetic field gradients", "operable magnetically", and "constituted in the fluid to correspond to the applied magnetic field The terms "shift in the direction of the gradient" are synonymous. They refer to particles that migrate in the liquid dispersion medium and may form chains once a magnetic field gradient is applied. In the scientific literature, such particles may be called magnetophoretic particles.

According to an embodiment of the present invention, the electrophoretic medium may include a dispersion of a plurality of charged particles. The plurality of electrophoretic particles preferably include at least three different groups of particles: light-scattering white pigments, light-scattering magnetic colored pigments, and black pigments. The colored pigment may be any color other than white or black. In a preferred embodiment, the colored pigment is red or yellow. In order to control the mobility of each group of charged particles through the dispersion fluid, more than one group of particles may contain a core pigment with a polymer coating, which is usually grafted or adsorbed on The surface polymers of the pigment particles are, for example, those described in U.S. Patent Application Publication Nos. 2015/0103394 and 2016/0085121. The diameters of the core pigments and/or the thickness of the coatings can be different among the groups of charged particles.

In a preferred embodiment of the present invention, the black pigment and the light-scattering magnetic coloring pigment have the same charge polarity, while the white pigment has the opposite polarity, and only the light-scattering magnetic coloring pigment is responsive to the magnetic field gradient, namely It moves in the direction corresponding to the applied magnetic field gradient within the dispersion fluid.

The core pigment used in the white particles may be a metal oxide with a high refractive index as well known in the field of electrophoretic displays. Examples of the material of the white particles include, but are not limited to, inorganic pigments, such as TiO ₂ , ZrO ₂ , ZnO, Al ₂ O ₃ , Sb ₂ O ₃ , BaSO ₄ , PbSO ₄ or the like.

The material of the black particles used as the core pigment includes but is not limited to: CI Pigment Black 26 or 28 or the like (for example, manganese ferrite black spinel or copper chromite black Spinel) or carbon black.

The colored pigment particles are preferably non-black and non-white, and may have colors such as red, green, blue, magenta, cyan, or yellow. The material used as the core pigment of the light-scattering magnetic color pigment includes but is not limited to: CI pigment PR 254, PR122, PR149, PG36, PG58, PG7, PB28, PB15:3, PY138, PY150, PY155 or PY20. They are commonly used organic pigments described in the color index manuals "New Pigment Application Technology" (CMC Press Co., Ltd., 1986) and "Ink Technology" (CMC Press Co., Ltd., 1984). Specific examples include: Clariant Hostaperm Red D3G 70-EDS, Hostaperm Pink E-EDS, PV fast red D3G, Hostaperm red D3G 70, Hostaperm Blue B2G-EDS, Hostaperm Yellow H4G-EDS, Hostaperm Green GNX, BASF Irgazine red L 3630, Cinquasia Red L 4100HD, and Irgazin Red L 3660HD; Solar Chemical Phthalocyanine Blue, Phthalocyanine Green, Diaryl Yellow or Diaryl AAOT Yellow. Examples of composite magnetic particles may include the materials described in US Patent No. 7,130,106.

In addition to these colors, the first, second, and third charged particles can also have other different optical characteristics, such as optical transmission, reflection, luminescence, or in the case of a display intended for machine reading, False color in the sense of changes in the reflection of electromagnetic wavelengths outside the visible range.

The plurality of charged pigment particles may be naturally charged or charged by the presence of a charge control agent.

The percentage of the charged particles in the fluid can be changed. For example, in a dispersion containing three kinds of particles, the black particles may account for about 0.1% to 10% of the volume of the electrophoretic fluid, preferably 0.5% to 5%; the white particles may account for about 1% of the volume of the fluid. % To 50%, preferably 5% to 15%; and the colored particles may account for about 2% to 20% of the volume of the fluid, preferably 1% to 10%.

The electrophoretic medium manufactured according to the various embodiments of the present invention may further contain one or more other optional components, such as uncharged neutral buoyant particles (such as those described in U.S. Patent Application 2015/0103394 ), charge control agents, and surfactants.

In a preferred embodiment of the present invention, the fluid is a non-polar solvent. The dispersion fluid in which the plurality of particles are dispersed may be a transparent and colorless solvent. In terms of high particle mobility, the solvent preferably has a low viscosity and a dielectric constant in the range of about 2 to about 30 (preferably about 2 to about 15). Examples of suitable dielectric solvents include: hydrocarbons (such as isoparaffin (Isopar), decalin (DECALIN), 5-ethylidene-2-norbornene, fatty oil, paraffin oil, silicon liquid), aromatic Hydrocarbons (such as toluene, xylene, phenylxylylethane, dodecylbenzene or alkylnaphthalene), halogenated solvents (such as perfluorodecalin, perfluorotoluene, perfluoroxylene, dichlorotrifluoro Toluene, 3,4,5-trichlorotrifluorobenzene, chloropentafluorobenzene, dichlorononane or pentachlorobenzene), and perfluorinated solvents (such as FC-43, from 3M Company, St. Paul Minn.) FC-70 or FC-5060), low molecular weight halogen-containing polymers (such as poly(perfluoropropylene oxide) from TCI USA, Portland, Oreg.), poly(chlorotrifluoroethylene) (such as from Halocarbon Products, River Edge, NJ's Halocarbon Oils), perfluoropolyalkyl ethers (such as Galden from Ausimont or Krytox oils and greases K-Fluid series from DuPont, Del.), polydimethylsiloxane-based from Dow-corning Silicone oil with oxane (DC-200).

As described above, the two charged pigment particles in the preferred embodiment of the present invention may have opposite charge polarities. In addition, the third type of charged pigment particles can be slightly charged. The term "slightly charged" means that the degree of charge of the particles is less than about 50% of the charge intensity of the stronger charged particles, preferably about 5% to about 30%. In one embodiment, the charge intensity can be measured in the form of zeta potential. In one embodiment, the interface potential is measured by a Colloidal Dynamics AcoustoSizer ΠM, ESA EN# Attn flow through cell (K: 127) with a CSPU-100 signal processing unit. Enter the instrument constants before the test, such as the density of the solvent used in the sample, the dielectric constant of the solvent, the speed of sound in the solvent, and the viscosity of the solvent, all of which are constants at the test temperature (25°C). The pigment sample is dispersed in the solvent (which is usually a hydrocarbon fluid with less than 12 carbon atoms) and diluted to between 5-10% by weight. The sample also contains a charge control agent (Solsperse® 17000, available from Lubrizol Corporation, Berkshire Hathaway) at a weight ratio of the charge control agent to the particles of 1:10. The mass of the diluted sample is measured, and then the sample is loaded into the flow cell to determine the interface potential.

In the context of the present invention, the term "critical voltage" or "electric field critical value" is defined as: when a pixel is driven from a color state different from the color state of a group of particles, it can be applied to the group of particles for a period of time (usually not longer than 30 seconds, preferably no longer than 15 seconds) without the particles appearing at the maximum electric field on the viewing side of the pixel. In this application, the term "viewing side" refers to the first surface in the display layer where the image can be seen by the viewer.

The threshold voltage or electric field threshold is an inherent characteristic of the charged particles or a property induced by additives.

In the former case, the threshold voltage or the threshold value of the electric field depends on the attraction between oppositely charged particles or between the particles and the surface of certain substrates.

In the case of the threshold voltage or the threshold value of the electric field caused by the additive, a threshold agent that initiates or strengthens the threshold characteristics of the electrophoretic fluid can be added. The critical agent can be any material that can be dissolved or dispersed in the solvent, or the solvent mixture of the electrophoretic fluid and the carrier, or induce a charge opposite to the charge of the charged particles. The critical agent may be sensitive or insensitive to changes in the applied voltage. The term "critical agent" can generally include dyes or pigments, electrolytes or polyelectrolytes, polymers, oligomers, surfactants, charge control agents, and the like. Additional information about the critical agent can be found in US Patent No. 8,115,729.

In one example, the electrophoretic medium may contain white pigment particles with a first charge of negative polarity, black pigment particles with a second charge of positive polarity, and red pigment particles with a third charge of positive polarity. If the red pigment particles are slightly charged, as described above, that is, the red pigment particles have a weaker charge than the charges on the black and white pigment particles, then the black particles are required to move to the electrophoretic medium. The viewing side may require a "critical voltage" applied to the entire electrophoretic medium instead of the lower voltage required for the red particles to move to the viewing side of the electrophoretic medium. Similarly, when the voltage potential difference applied between the light-transmitting conductive layer and the pixel electrode generates an electric field that is weaker than the critical value of the electric field and has the polarity that drives the red particles to abut the light-transmitting conductive layer, it may be more The strong electrostatic attraction between the black particles and the white particles that is smaller than the electrostatic attraction between the red particles and the white particles can cause the red particles to migrate to abut the light-transmitting conductive layer. Applying a voltage potential difference between the light-transmitting conductive layer and the pixel electrode to generate an electric field stronger than the critical value of the electric field (and having the polarity to drive the black particles to abut the light-transmitting conductive layer) can fully overcome the white and black The electrostatic attraction between the particles causes the black particles to migrate to abut the light-transmitting conductive layer.

The three kinds of charged particles can have various sizes. In one embodiment, one of the three particles is larger than the other two. For example, the black and white particles can be relatively small and their size (tested by dynamic light scattering) can be in the range of about 50nm to about 800nm (more preferably about 200nm to about 700nm), and the The iso-colored particles are preferably about 2 to about 50 times and more preferably about 2 to about 10 times larger than the black particles and the white particles. These values correspond to the average diameter of the corresponding pigment particles.

As explained above, the electrophoretic medium according to various embodiments of the present invention can be incorporated into a writable electro-optical display using more than one writing instrument. The writing instrument may be hand-held. At least one of the writing instruments can generate an electric field and/or a magnetic pole, which causes a change in the optical state of the display in the local area where the writing instrument is located. The change in the optical state may include the movement of the white, colored, and/or black particles in the display.

Referring now to FIG. 1, a display according to an embodiment of the present invention may include a dispersion including a plurality of electrophoretic particles between the first conductive layer 100 and the second conductive layer 102. As shown in FIG. 1, the display is viewed from above; therefore, the first conductive layer 100 may be a continuous layer of light-transmitting conductive material, such as indium tin oxide. The second conductive layer 102 may be light-transmissive or opaque. For example, the layer 102 may be provided in the form of a substrate including an array of pixel electrodes, such as a TFT array. The display may further include a touch sensing layer 101 (such as a touch sensor) for sensing the contact of the writing implement 114.

For example, the electrophoretic particles may include: negatively charged white pigment particles 104, positively charged black pigment particles 108, and positively charged light-scattering magnetic colored pigment particles 106. As those skilled in the art can understand, in some examples, the polarity of the charges of the particles may be opposite, such as the white pigments are positively charged, but the black and magnetic particles are negatively charged. If the writable display is intended to include a highlighting function, for example, the color of the magnetic particles 106 may be red.

Referring now to FIGS. 1 to 3, the display according to an embodiment of the present invention can be combined with three different styluses 110, 112, and 114. The stylus 110 may be a magnetic stylus for writing the eye-catching color. The stylus 112 may be non-magnetic and used for writing black, while the stylus 114 may be non-magnetic and used for writing white. Or, all three functions can be included in a single writing instrument. For example, a single stylus may have a magnetic end for making eye-catching reminders, and an opposite end that can be switched between writing black or white. In FIGS. 1 to 3, the stylus pens are exemplified as hemispherical tips with similar shapes; however, the writing tips of the writing instruments described herein are not limited to any specific shape. For example, each stylus may have a unique tip shape that can be detected by the touch sensing layer, so that the display can recognize which stylus is being used.

For all three probe options, the touch sensing layer 101 can not only sense, but also record the writing position, so that this information can be digitized and stored in the memory, so that the user can decide to change The written image is stored, captured and displayed.

According to a method of operating a display of the present invention, a writing instrument can be used or not to control the optical states displayed on various positions of the display. The first optical state shown in FIG. 1 can be achieved by the following method: touching the surface of the display with the stylus 114 so that the touch sensing layer 101 recognizes the stylus 114 and its position. At this position, a voltage is applied between the electrode layers 100 and 102 so that the electrode layer 102 is negative with respect to the electrode 100. As a result, the white particles 104 are driven toward the viewing side of the display to display a white optical state near the area contacted by the stylus 114. For example, the negative voltage can be applied between the electrode layer 100 and the pixel electrodes in the area corresponding to the position of the stylus 114 where only the electrode layer 102 is located. In this way, for example, the stylus 114 can be used as an "erasing stylus" to achieve partial erasing of black or red images. Full erasure can be achieved by, for example, the following method: without using the stylus, a negative voltage is applied between each pixel electrode in the electrode layer 102 and the electrode layer 100 at the same time.

The second optical state shown in FIG. 2 can be achieved by the following method: touching the surface of the display with a stylus pen 110. As described above, the type and position of the stylus can be detected by the touch sensing layer 101. When the stylus 110 is recognized, the electrophoretic fluid is not electrically switched (ie, no voltage difference is applied between the electrodes 100 and 102). More specifically, the colored magnetic particles 106 move in the magnetic field gradient generated by the approach of the stylus 110. Such movement usually provides a "chained-particle" state, in which some particles on the viewing side (for example, the white pigment particles 104 in FIG. 2) have been replaced by the colored particles 106.

In some embodiments, the magnet included in the stylus 110 may be a permanent magnet. The magnet can have any suitable type, including but not limited to: neodymium iron boron, samarium cobalt, alnico magnet (alnico), ceramics and ferrite magnets, or a combination thereof. Although the magnet can be arranged at any position of the stylus, it is preferable to position the magnet so that its magnetic field is co-aligned with the tip of the stylus. According to some embodiments, the magnet may be an electromagnet. In this case, a suitable power source can be configured in the stylus or electrically connected to the stylus and the magnet is in the stylus. Furthermore, the magnet can have any suitable shape, including cube or ring. According to some embodiments, the magnet will generate a field gradient between about 10 and 50 Gauss on the magnetic particles.

The third optical state shown in FIG. 3 can be achieved by the following method: touching the surface of the display with the stylus pen 112 so that the touch sensing layer 101 recognizes the stylus 112 and its position. At this position, a voltage is applied between the electrode layers 100 and 102 so that the electrode layer 102 is positive with respect to the electrode 100. As a result, the black particles 104 are driven toward the viewing side of the display to display a black optical state near the area contacted by the stylus pen 112. For example, the positive voltage can be applied between the electrode layer 100 and the pixel electrodes in the area corresponding to the position of the stylus 112 of the electrode layer 102 only. In this way, for example, the stylus 112 can be used as a "writing stylus" so that the user can use the display to take notes.

In a preferred embodiment, the black pigment particles 108 may have a diameter smaller than the diameter of the light-scattering magnetic colored pigment particles 106, and they have the same charge polarity. For example, referring again to FIG. 3, if the black pigment particles 108 and colored magnetic particles 106 are both positively charged, a positive voltage with sufficient strength and/or duration can be applied to allow the smaller black particles 108 to pass through the The space between the magnetic particles 106 migrates to the viewing side of the display to shield the colored particles 106.

In order to capture stored images containing pixels with optical states provided by the colored magnetic particles, it may be preferable that the colored magnetic particles have a higher level than the similarly charged black particles The degree of mobility. This can be done by applying different polymer coatings to the colored and black particles and/or providing slightly charged black particles. For example, referring to FIG. 4, a voltage is applied between the electrode layers 100 and 102 so that the electrode layer 102 is positive with respect to the electrode layer 100. However, the intensity and/or duration of the applied voltage is lower than the preselected critical value, so that the colored magnetic particles 106 are driven to the viewing side of the display, instead of the white particles 104 or the black particles that may be agglomerated together. Particles 108. In order to provide pixels with the optical states provided by the white or black particles in the stored image, a negative voltage of sufficient intensity and/or duration can be applied to drive the white particles 104 to the viewing surface, or it can be applied A positive voltage of sufficient strength and/or duration to drive the black particles 108 between the colored particles 106 and the viewing surface (as shown in FIG. 5).

Table 1 below summarizes examples of various modes of writing/capturing images on a display according to an embodiment of the present invention. W represents white, K represents black, and R represents colored magnetic particles.

Table 1:

The electro-optical device includes: a first type of particles with a first color and a first charge of a first charge polarity (positively charged white particles in the example corresponding to the table); and a second color, a second The second type of particle of the second charge of the charge polarity (in the example corresponding to the table, the negatively charged black particle, which has the critical value of the electric field); the third charge of the third charge with the third color and the second charge polarity Three kinds of particles (in the example corresponding to the table, negatively charged red particles, which are configured to migrate in the fluid in the direction corresponding to the applied magnetic field gradient), can be operated by a method including the following steps : (A) Touch one of the first and second stylus pens to the first position on the first surface of the device; (B) Apply an electric field to make the first (white) and second ( (Black) one of the particles migrates toward the first position; (C) contacting one of the first and second stylus pens with a second position on the first surface of the display; and (D) applying The magnetic field gradient causes the third particles (red) to migrate toward the second position.

In another embodiment, the electro-optical device includes an electrophoretic medium including negatively charged white particles 604, positively charged red particles 606, and positively charged black magnetic particles 608. It can be observed that starting from the white state (FIG. 6 ), and touching the writable surface of the electro-optical display with the magnetic stylus 110 once, a gray image is generated. The magnetic stylus attracts the magnetic black particles 608 and aligns them, as shown in FIG. 7. After applying the magnetic stylus more than one time to the same position on the writable surface of the electro-optical device where the gray color exists, the color of the position becomes red. It is illustrated in the photos in Figs. 8 and 9. A magnetic stylus is used to touch the electro-optical device 900 of FIG. 9 with its white state 901 as its original state and write the word "magnetic addressing" 902 on it. The word appears gray. At another location of the electro-optical device 900, a magnetic stylus is used to draw a picture 903. At the position of the picture 903, the stylus touches the electro-optical device several times. The picture 903 appears red. The electrophoretic medium of this embodiment is prepared by using Isopar E as the electrophoretic fluid, which includes: (a) Solsperse 19000 (provided by Lubrizol) as a charge control agent, (b) positively charged iron oxide black magnetic pigment (pigment) Black 11), (c) negatively charged titanium dioxide white pigment (Pigment White 6), and (d) negatively charged red (Pigment Red 254). When the initial optical state is black, touch the writable surface of the electro-optical display with a magnetic stylus once to produce a red image, which is the same as when the magnetic stylus is applied to the writable surface of the electro-optical device The position becomes brighter red after more than one position. Figure 9 shows an exemplary operation of the display.

This embodiment records an electro-optical device including (a) an electrophoretic medium, the electrophoretic medium is disposed between a light-transmissive conductive layer and an array of pixel electrodes, and includes a plurality of particles in a fluid, and the plurality of particles include:( 1) A first type particle with a first color and a first charge polarity; (2) a second type particle with a second color and a second charge polarity; and (3) a third Color, the second charge polarity and the third charge particles, wherein the first, second and third colors are different from each other, wherein the first charge polarity is opposite to the second charge polarity, wherein The plurality of particles are configured to migrate in the fluid in a direction corresponding to the applied electric field, and the third type of particles are configured to move in the fluid in a direction corresponding to the applied magnetic field gradient migrate. The electro-optical device can be operated by a method including the following steps: (A) Touch a stylus with a magnetic tip to a first position on the first surface of the device so that the third particles migrate toward the first position; And (B) contacting the first position on the first surface of the device with the stylus including the magnetic tip again to make the second kind of particles migrate toward the first position. This method allows users to use two different colors to write or draw pictures on the device.

The dispersions of electrophoretic media according to various embodiments of the present invention may be encapsulated. The encapsulated electrophoretic medium includes a large number of small capsules, and each small capsule itself includes an internal phase and a capsule wall surrounding the internal phase. The internal phase contains electrophoretic movable particles in the fluid medium. Usually, the capsules themselves are held in a polymeric adhesive to form an adhesive layer between the two electrodes. In a microcell electrophoretic display, the charged particles and the fluid are not encapsulated in microcapsules, but instead remain in a plurality of cavities formed in a carrier medium (usually a polymer film). As disclosed in US Patent No. 6,933,098, the micelles can be formed in a batch process or a continuous roll-to-roll process. The latter provides continuous, low-cost, high-capacity manufacturing technology to make compartments. The micelles can be manufactured by embossing, photolithography, contact printing, vacuum forming, or other suitable methods. In this configuration, the micelles can be sandwiched between the light-transmitting conductive layer and the array of pixel electrodes. In one embodiment, the microcells are manufactured separately and then arranged between the transparent conductive layer and the array of pixel electrodes. For example, the microcellular structure can be manufactured by embossing. The embossing is often done by a male mold, which can be in the form of a roll, a plate, or a belt. The embossed composition may include a thermoplastic substance, a thermosetting substance or a precursor thereof. The embossing process is usually performed at a temperature higher than the glass transition temperature of the microcellular material. A heated male mold or a heated housing substrate against which the mold is pressed can be used to control the embossing temperature and pressure. The male mold is often formed of a metal such as nickel. Once formed, the micelles are filled with the electrophoretic medium. Then, the filled micelles are sealed and the sealed micelles are laminated between the light-transmitting conductive layer and the array of pixel electrodes.

Encapsulated electrophoretic displays generally do not encounter the aggregation and sedimentation failure modes of traditional electrophoretic devices, and provide additional advantages such as the ability to print or coat the display on a wide variety of flexible and rigid substrates. (The term "printing" is used to include all forms of printing and coating, including but not limited to: pre-metered coating such as patch die coating, slit or extrusion coating, sliding or layered coating , Curtain coating; roll coating such as knife over roll coating, forward and reverse roll coating; gravure coating; dip coating; spray coating; meniscus coating; spin coating; brush coating; Air knife coating; screen printing process; electrostatic printing process; thermal printing process; inkjet printing process; electrophoretic deposition (see US Patent No. 7,339,715); and other similar technologies.) Therefore, the resulting display can be flexible. In addition, since various methods can be used to print the display medium, the display itself can be manufactured inexpensively.

Other types of electro-optical media can also be used for the display of the present invention.

The manufacture of three-layer electro-optical displays generally involves at least one layering operation. For example, in several of the aforementioned MIT and E Ink patents and applications, a process for manufacturing an encapsulated electrophoretic display is described, in which an encapsulated electrophoretic medium including a capsule in an adhesive is coated on a flexible substrate, and the flexible substrate includes Indium tin oxide (ITO) or similar conductive coating on the plastic film (which serves as an electrode of the final display), the capsule/adhesive coating is dried to form an adhesion of the electrophoretic medium tightly attached to the substrate Floor. In addition, a backplane is prepared which contains an array of pixel electrodes and a suitable conductor arrangement to connect the pixel electrodes to the driving circuit. In order to form the final display, the substrate with the capsule/adhesive layer thereon is laminated on the back plate using a laminated adhesive. (A very similar process can be used to prepare an electrophoretic display that can be used with a stylus or similar movable electrodes, by replacing the back plate with a simple protective layer such as a plastic film, the stylus or other The movable electrode can slide on the protective layer.) In a preferred form of such a process, the back plate itself is flexible and is prepared by printing the pixel electrodes and conductors on a plastic film or other flexible substrate. The lamination technology for mass production of displays using this process is roll lamination using lamination adhesives. Similar manufacturing techniques can be used with other types of electro-optical displays. For example, the microcellular electrophoresis medium can be layered on the back plate in substantially the same manner as the encapsulated electrophoretic medium.

The aforementioned US Patent No. 6,982,178 describes a method for assembling a solid-state electro-optical display (including a packaged electrophoretic display), which is very suitable for mass production. Basically, this patent describes the so-called "front plate laminate" ("FPL"), which in turn includes: a light-transmitting conductive layer; a solid electro-optical dielectric layer in electrical contact with the conductive layer; an adhesive layer; and a release sheet (release sheet). Usually the light-transmitting conductive layer is placed on a light-transmitting substrate. In the sense that the substrate can be manually wound on a 10-inch (254mm) diameter drum (say) without permanent deformation, it is preferably flexible of. The term "translucent" used in this patent and in this article refers to a layer designated by it that allows enough light to pass through so that the observer can see through the layer and observe the change in the display state of the electro-optical medium, which generally passes through the conductive The layer and the adjacent substrate (if present) are viewed; in the case that the electro-optical medium shows a change in reflection at a non-visible light wavelength, of course the term "transparent" should be interpreted as meaning the transmission of the relevant non-visible light wavelength . The substrate is usually a polymeric film and generally has a thickness in the range of about 1 to about 25 mils (25 to 634 μm), preferably about 2 to about 10 mils (51 to 254 μm). The conductive layer is suitably a thin metal or oxide metal layer such as aluminum or ITO, or may be a conductive polymer. Poly(ethylene terephthalate) (PET) films coated with aluminum or ITO are commercially available, for example, "Aluminized Mylar" ("Mylar" is a registered trademark) from EI du Pont de Nemours & Company, Wilmington DE Trademark), and this commercially available material can be effectively used for the front plate laminate.

The components of the electro-optical display using this front-plate laminate can be realized by removing the release sheet from the front-plate laminate, and under the condition that the adhesive layer is effectively attached to the back plate. The adhesive layer is in contact with the back plate, thereby firmly fixing the adhesive layer, the electro-optical medium layer and the conductive layer to the back plate. Because the front plate laminate can be mass-produced, this process is very suitable for mass production, usually using roll-to-roll coating technology, and then cutting into pieces with any size required for use with a specific backing plate.

US Patent No. 7,561,324 describes a so-called "double release sheet", which is basically a simplified version of the front plate laminate of the aforementioned US Patent No. 6,982,178. One form of the double release sheet includes a solid electro-optical medium layer sandwiched between two adhesive layers, one or two of the adhesive layers being covered by the release sheet. Another form of the double release sheet includes a solid electro-optical medium layer sandwiched between two adhesive sheets. The two forms of the double release film are intended to be used in a process roughly similar to the process of assembling an electro-optical display from the front plate laminate, but involves two separate laminations; usually, in the first In the lamination operation, the double release sheet is laminated on the front electrode to form a front sub-assembly, and then in the second lamination operation, the front sub-assembly is laminated on the back plate to form the final display. However, If necessary, you can reverse the order of these two build-up operations.

U.S. Patent No. 7,839,564 describes a so-called "inverted front plane laminate", which is a deformation of the front plane laminate described in the aforementioned U.S. Patent No. 6,982,178. The inverted front plate laminate sequentially includes: at least one of a light-transmitting protective layer and a light-transmitting conductive layer; an adhesive layer; a solid electro-optical medium layer; and a release sheet. This inverted front plate build-up system is used to form an electro-optical display, which has: a build-up adhesive layer between the electro-optical layer and the front electrode or front substrate; a second adhesive layer, which is usually thin and may exist or It does not exist between the electro-optical layer and the backplane. This kind of electro-optical display can combine good resolution and good low temperature performance.

In the above-mentioned manufacturing process, it may be advantageous to laminate the substrate with the electro-optical layer on the backplane by vacuum lamination. The vacuum lamination system effectively exhausts air from between the two materials to be laminated, thereby preventing unwanted bubbles from appearing in the final display; such bubbles may introduce undesirable artifacts into the display In the image produced on the above. However, vacuum lamination of the two parts of the electro-optical display in this way, especially in the case of a display using an encapsulated electro-optical medium, imposes strict requirements on the laminated adhesive used. The laminated adhesive should have sufficient bonding strength to bond the electro-optic layer to the layer (usually the electrode layer) to be laminated, and in the case of the encapsulated electrophoretic medium, the adhesive should have sufficient bonding strength to The capsule is held together mechanically. If the electro-optical display is to be made into a flexible type, the adhesive should have sufficient flexibility so as not to introduce defects into the display when the display is bent. At the temperature of the build-up, the build-up adhesive should have appropriate flow properties to ensure high-quality build-up. At this point, the electrophoresis of the build-up package and the requirements of some other types of electro-optical media are very difficult; in order to avoid this The medium is damaged and cannot be exposed to a substantially higher temperature. Therefore, the lamination operation must be carried out at a temperature not higher than about 130°C, but the flow of the adhesive must be sufficient to cope with the relative temperature of the capsule-containing layer. A flat surface. The surface of the capsule-containing layer is uneven due to the underlying capsule. The temperature of the build-up layer should be kept as low as possible, and room-temperature build-up is ideal, but there is no commercially available adhesive that can tolerate such room-temperature build-up. The build-up adhesive should be chemically compatible with all other materials in the display.

Therefore, several aspects and embodiments of the technology of the present application have been described, and it should be understood that various changes, modifications and improvements can be easily thought of by those with ordinary knowledge in the art. Such changes, modifications and improvements are intended to fall within the spirit and scope of the technology described in this application. For example, a person with ordinary knowledge in the art can easily come up with a variety of other means and/or structures to perform the functions described herein and/or obtain the results described herein and/or more than one advantage, and each such variation And/or modifications are deemed to fall within the scope of the embodiments described herein. Those with ordinary knowledge in the field can confirm or determine many equivalents of the specific embodiments described herein by using routine experiments. Therefore, it should be understood that the foregoing embodiments are only presented as examples, and innovative embodiments may be implemented in different methods from the specifically described embodiments within the scope of the attached patent application and its equivalents. . In addition, any combination of two or more features, systems, articles, materials, tools, and/or methods described herein, if such features, systems, articles, materials, tools, and/or methods are not incompatible with each other , Is included in the scope of this disclosure.

100: the first conductive layer 101: touch sensing layer 102: second conductive layer 104: Negatively charged white pigment particles 106: Positively charged light scattering magnetic colored pigment particles 108: Positively charged black pigment particles 110, 112, 114: stylus 114: writing utensils 604: Negatively charged white particles 606: Positively charged red particles 608: Positively charged black magnetic particles 900: Electro-optical device 901: white state 902: Word 903: picture

Various aspects and embodiments of this application will be described with reference to the following drawings. It should be understood that these drawings are not necessarily drawn to scale. Items that appear in multiple drawings are assigned the same reference symbols in all the drawings in which they appear.

FIG. 1 illustrates a cross-sectional view of an addressable electro-optic display combined with a first stylus according to a first embodiment of the present invention.

FIG. 2 illustrates a cross-sectional view of the operable electro-optical display of FIG. 1 combined with a second stylus.

FIG. 3 illustrates a cross-sectional view of the operable electro-optical display of FIG. 1 combined with a third stylus.

FIG. 4 illustrates a cross-sectional view of the operable electro-optical display of FIG. 1 showing a first optical state.

FIG. 5 illustrates a cross-sectional view of the operable electro-optical display of FIG. 1 showing a second optical state.

FIG. 6 illustrates a cross-sectional view of the operable electro-optical display in a white state.

FIG. 7 illustrates a cross-sectional view of the operable electro-optical display of FIG. 6 combined with a second stylus pen (touching the stylus once).

FIG. 8 illustrates a cross-sectional view of the operable electro-optical display of FIG. 6 combined with a second stylus (the stylus is touched more than once).

Figure 9 shows a photograph of an operable electro-optical display capable of writing and drawing pictures when touched by a magnetic stylus.

none.

Claims (20)

An electro-optical device, comprising: a first surface on the viewing side; a second surface on the opposite side of the first surface; an electrophoretic medium, arranged between a light-transmitting conductive layer and an array of pixel electrodes, and including a fluid A plurality of particles in the plurality of particles, the plurality of particles include: a first type of particles having a first color, a first charge polarity, wherein the first color is white; a second color, a second charge polarity A second particle of a second charge; and a third particle of a third charge with a third color and a polarity of the second charge; wherein the first, second, and third color systems are different from each other; the polarity of the first charge The polarity of the second charge is opposite; the plurality of particles are configured to move in one direction in the fluid in response to an applied electric field; the third particles are configured to move in the fluid in response to an applied magnetic field gradient Migrate in one direction; the second kind of particles do not respond to the magnetic field gradient; the second kind of particles have an electric field threshold, so that (a) a voltage potential difference is applied between the light-transmitting conductive layer and the pixel electrode potential difference) to generate an electric field that is stronger than the critical value of the electric field and has the polarity to drive the second type particles adjacent to the light-transmitting conductive layer, so that the pixel corresponding to the pixel electrode displays the Second color (b) Applying a voltage potential difference between the light-transmitting conductive layer and the pixel electrode to generate an electric field that is stronger than the critical value of the electric field and has a polarity that drives the first type particles adjacent to the light-transmitting conductive layer, and The pixel corresponding to the pixel electrode displays the first color on the first surface; (c) Once the first color is displayed on the first surface, a voltage potential difference is applied between the light-transmissive conductive layer and the pixel electrode to generate An electric field that is weaker than the critical value of the electric field and has the polarity to drive the third particles adjacent to the light-transmitting conductive layer will cause the pixels corresponding to the pixel electrode to display the third color; wherein once the first color Is displayed at the first position on the first surface, touching the first position with a second stylus with a magnetic tip once will cause the third particles to migrate toward the first position; and once the first position The three kinds of particles migrate toward the first position due to the second stylus touching the first position, and then using the second stylus to move back and forth again to touch the first position with the second stylus to make The second kind of particles migrate towards the first position. The electro-optical device of claim 1, wherein during the time when the second stylus is in contact with the first position, the light-transmitting conductive layer and the pixel electrodes do not apply an electric field on the electrophoretic medium at the first position. The electro-optical device of claim 1, wherein contacting the second position of the first surface with a first stylus with a non-magnetic tip causes the first type of particles to migrate toward the second position, wherein the second position and the first A position is the same or different from the first position. The electro-optical device of claim 3, wherein contacting the third position of the first surface with a third stylus with a non-magnetic tip causes the second kind of particles to migrate to the third position, wherein the third position and the third position One position is the same or the second position Set differently. The electro-optical device of claim 1, wherein the second stylus touches the first position on the first surface, causing the third type of particles to form a chain. Such as the electro-optical device of claim 1, wherein the second color is black. Such as the electro-optical device of claim 1, wherein the third color is red, green, blue, magenta, cyan, or yellow. Such as the electro-optical device of claim 1, wherein the third color is black, and the second color is red, green, blue, magenta, cyan, or yellow. The electro-optical device of claim 1, wherein the average diameter of the particles of the third type is greater than the average diameter of the particles of the second type. The electro-optical device of claim 1, wherein the fluid is a non-polar solvent. The electro-optical device of claim 1, wherein the device is configured to display at least one color when the non-magnetic tip contacts the surface of the display. The electro-optical device of claim 1, wherein the device is configured to display at least two colors. A method of operating an electro-optical device, wherein the electro-optical device comprises: (a) a first surface on the viewing side; (b) a second surface on the opposite side of the first surface; (c) an electrophoretic medium arranged in A plurality of particles between the light-transmitting conductive layer and the pixel electrode array and included in the fluid, the plurality of particles including: (1) a first type of particle with a first color and a first charge polarity , Wherein the first color is white; (2) a second particle with a second color and a second charge with a second charge polarity; and (3) a third color with a third charge with the second charge polarity The third kind of particles; wherein the first, second and third colors are different from each other; wherein the polarity of the first charge is opposite to the polarity of the second charge; Wherein the plurality of particles are configured to migrate in a direction in the fluid in response to an applied electric field; and wherein the third particles are configured to migrate in a direction in the fluid in response to an applied magnetic field gradient; the The method includes the following steps: once the first color is displayed at the first position on the first surface, a second stylus with a magnetic tip is used to touch the first position once, so that the third particle faces the first position. A position shift; once the third particle moves toward the first position due to the second stylus contacting the first position, use the back and forth movement of the second stylus to move the second stylus again Contacting the first location causes the second type of particles to migrate toward the first location. The method for operating an electro-optical device according to claim 13, wherein during the time when the second stylus is in contact with the first position, the light-transmitting conductive layer and the pixel electrodes do not apply an electric field at the first position to the electrophoretic medium superior. For example, the method of operating an electro-optical device of claim 13, further comprising the following steps: contacting a second position on the first surface of the electro-optical device with a first stylus with a non-magnetic tip to make the first particles face the first Two positions are shifted, wherein the second position is the same as the first position or different from the first position. For example, the method of operating an electro-optical device of claim 13, further comprising the steps of: contacting a third position on the first surface of the electro-optical device with a third stylus with a non-magnetic tip to make the second particles move toward the first surface of the electro-optical device. Three-position migration, wherein the third position is the same as the second position or different from the second position. Such as the method of operating an electro-optical device in claim 13, when it is magnetic When the tip of the second stylus touches the first position on the first surface on the viewing side of the electro-optical device once, the third type of particles forms a chain. Such as the method of operating an electro-optical device of claim 13, wherein the second color is black. For example, the method of operating an electro-optical device of claim 13, wherein the third color is red, green, blue, magenta, cyan or yellow. For example, the method of operating an electro-optical device of claim 13, wherein the third color is black, and the second color is red, green, blue, magenta, cyan, or yellow.

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